Well, the reason I could swear that it hit around the 60s was because I recalled that the pokemon, Tangela, had learned Power Whip and continued to level up. Checking Bulbapedia, Tangela learns it at level 54 in White, which needs 157464 EXP, and is thus above the cap.
I tried to calculate the amount of EXP I'd get from the battle in White, but I have a feeling that the Metalkid calc is broken since it's giving me more experience from Audino than Blissey. So I tried plugging in values from the equation in Bulbapedia and it gives me enough EXP to reach 56.
Then again, the Bulbapedia page does say "In Generation V, it is impossible to gain more than 100,000 experience from any single Pokémon.", so I guess I just mistook Power Whip for... Slam, I guess? Ah well, either way, still ultimately evolved my Larvesta after another Breeder battle, so it doesn't really matter anymore.
Man, I should really be studying for exams or sleeping instead of spending time calculating pointless stuff....